Dr. Steve WaiChing Sun
Department of Civil Engineering & Engineering Mechanics
Columbia University in the City of New York, USA
Date:6th January 2015, Tuesday
Venue: Room 3574 (lift 27 & 28, Conference Room) Academic Building The Hong Kong University of Science and Technology
The mechanical behavior of a fluid-infiltrating porous solid is significantly influenced by the presence and diffusion of the pore fluid in the void. This hydro-mechanical coupling effect can be observed in a wide range of materials, including rocks, soils, concretes, bones and soft tissues. Nevertheless, due to the high computational demand, explicitly simulating the pore scale solid-fluid interactions remains impractical for engineering problems commonly encountered in the field and basin scales. The objective of this talk is to present two classes of multiscale computer simulation technologies that allow the coupling of micro- and macro-scopic simulations across different spatial and temporal scales. The first class of model is a concurrent coupling model in which the deformation-diffusion problems are casted as the saddle point that optimizes the constrained partitioned incremental work of a multi-field energy functional. By introducing appropriate technology to enforce compatibility across length scales, pore-scale simulations in confined domain can be coupled with large-scale field problems while maintaining numerical stability and accuracy. The second class of multiscale model is a nonlocal hierarchical multiscale framework that couples grain-scale discrete element simulations with a macroscopic explicit dynamics finite element model. This hierarchical nonlocal DEM-FEM coupling retains the simplicity and efficiency of the continuum-based finite element model, while possessing the original length scale of the granular system. The pros and cons of these two different coupling strategies will be demonstrated in numerical examples.
Biography Dr. Steve Sun is an Assistant Professor in the Department of Civil Engineering at Columbia University. His research focuses on the development of solution techniques for coupled geomechanics problem, and applications of mathematical tools, such as graph theory, Lie algebra, and combined deterministic-stochastic method, for modern engineering problems.
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